The Collaborative International Dictionary of English v.0.48:

Abib \A"bib\, n. [Heb. ab[imac]b, lit. an ear of corn. The month
   was so called from barley being at that time in ear.]
   The first month of the Jewish ecclesiastical year,
   corresponding nearly to our April. After the Babylonish
   captivity this month was called Nisan. --Kitto.
   [1913 Webster]

Easton's 1897 Bible Dictionary:

Abib
   an ear of corn, the month of newly-ripened grain (Ex. 13:4;
   23:15); the first of the Jewish ecclesiastical year, and the
   seventh of the civil year. It began about the time of the vernal
   equinox, on 21st March. It was called Nisan, after the Captivity
   (Neh. 2:1). On the fifteenth day of the month, harvest was begun
   by gathering a sheaf of barley, which was offered unto the Lord
   on the sixteenth (Lev. 23:4-11).


Hitchcock's Bible Names Dictionary (late 1800's):

Abib, green fruit; ears of corn